[vtkusers] Make Smooth Isosurfaces

[Bill Lorensen]

I mean the unstructured grid (the geometry).

On Fri, Oct 30, 2009 at 12:10 PM, Sanket Jain <jainsanket1 at gmail.com> wrote:
> Ok. I will recheck my matlab program which writes the vtk file and get back
> to you.
>
> For Paraview, did you mean only the mesh points without the scalar values? I
> checked the unstructured grid with scalars on them. They look exactly the
> same as in my VTK code.
>
> Sanket
>
> On Fri, Oct 30, 2009 at 7:55 AM, Bill Lorensen <bill.lorensen at gmail.com>
> wrote:
>>
>> Perhaps your scalar values are not associated with the proper points?
>> Have you looked at the original unstructured grid with paraview?
>>
>> On Thu, Oct 29, 2009 at 10:21 PM, Sanket Jain <jainsanket1 at gmail.com>
>> wrote:
>> > Yes, I tried for number of isovalues. But all of them have similar
>> > characteristics. Is it anything to do with the vtk file being in
>> > unstructured grid rather than polygonal data? For the mesh, I imported
>> > from
>> > COMSOL, I cannot use polygonal data.
>> >
>> > Sanket Jain
>> > On Thu, Oct 29, 2009 at 6:33 PM, Bill Lorensen <bill.lorensen at gmail.com>
>> > wrote:
>> >>
>> >> It does look strange. Have you tried changing the isosurface value?
>> >>
>> >> On Thu, Oct 29, 2009 at 5:44 PM, Sanket Jain <jainsanket1 at gmail.com>
>> >> wrote:
>> >> > I have attached a snapshot of my viewer. The isosurface is predicting
>> >> > the
>> >> > volume activated during monopolar stimulation. So, theoretically you
>> >> > will
>> >> > expect a sphere at a particular iso value.
>> >> >
>> >> > I tried using vtkPolyDataNormals. The figure attached is the output
>> >> > after
>> >> > including this filter. But I still think this is not smooth.
>> >> >
>> >> > I verified by opening my vtk file in Paraview (with, Compute Normal
>> >> > ON).
>> >> > Even then i get the same kind of response. So, do you think this is
>> >> > the
>> >> > best
>> >> > i can get? Or there might be some problem in the vtk file which is
>> >> > exported
>> >> > from COMSOL (I verified it multiple times).
>> >> >
>> >> > Thank you,
>> >> >
>> >> > Sanket
>> >> >
>> >> > On Thu, Oct 29, 2009 at 4:01 PM, Bill Lorensen
>> >> > <bill.lorensen at gmail.com>
>> >> > wrote:
>> >> >>
>> >> >> Sorry, reading your e-mail in more detail. Are you generating the
>> >> >> isosurfaces in vtk using vtkContourFIiter or some equivalent. If so,
>> >> >> you should run the output through vtkPolyDataNormals.
>> >> >>
>> >> >> On Thu, Oct 29, 2009 at 4:59 PM, Bill Lorensen
>> >> >> <bill.lorensen at gmail.com>
>> >> >> wrote:
>> >> >> > What do you mean by rough? Perhaps the faces are flat shaded? How
>> >> >> > are
>> >> >> > you displaying the model in vtk?
>> >> >> >
>> >> >> > Are your isosurfaces composed of only triangles? If so, did you
>> >> >> > provide surface normals at each point?
>> >> >> >
>> >> >> > On Thu, Oct 29, 2009 at 4:30 PM, Sanket Jain
>> >> >> > <jainsanket1 at gmail.com>
>> >> >> > wrote:
>> >> >> >> Hello Experts,
>> >> >> >>
>> >> >> >> I have just started to use VTK to fulfill my visualization needs.
>> >> >> >> I
>> >> >> >> am
>> >> >> >> trying out few fundamental steps which would be crucial for my
>> >> >> >> future
>> >> >> >> development.
>> >> >> >>
>> >> >> >> I exported an  Finite Element Model (FEM) from COMSOL and wrote
>> >> >> >> it
>> >> >> >> as
>> >> >> >> vtk
>> >> >> >> unstructured grid in matlab (points, connections and data). I am
>> >> >> >> just
>> >> >> >> trying
>> >> >> >> to read my vtk file and trying to visualize the isosurfaces at
>> >> >> >> some
>> >> >> >> value.
>> >> >> >>
>> >> >> >> The problem is the isosurfaces are very rough even when I
>> >> >> >> increased
>> >> >> >> the
>> >> >> >> mesh
>> >> >> >> density in my COMSOL model. I tried to perform the same task in
>> >> >> >> paraview and
>> >> >> >> even there i saw the same problem.
>> >> >> >>
>> >> >> >> Do you think that increasing the mesh density should solve it? I
>> >> >> >> cannot
>> >> >> >> increase the mesh density because of computational issues. Any
>> >> >> >> ideas
>> >> >> >> on
>> >> >> >> this
>> >> >> >> problem will be appreciated.
>> >> >> >>
>> >> >> >> Thank you,
>> >> >> >>
>> >> >> >> Sanket Jain
>> >> >> >>
>> >> >> >> _______________________________________________
>> >> >> >> Powered by www.kitware.com
>> >> >> >>
>> >> >> >> Visit other Kitware open-source projects at
>> >> >> >> http://www.kitware.com/opensource/opensource.html
>> >> >> >>
>> >> >> >> Please keep messages on-topic and check the VTK FAQ at:
>> >> >> >> http://www.vtk.org/Wiki/VTK_FAQ
>> >> >> >>
>> >> >> >> Follow this link to subscribe/unsubscribe:
>> >> >> >> http://www.vtk.org/mailman/listinfo/vtkusers
>> >> >> >>
>> >> >> >>
>> >> >> >
>> >> >
>> >> >
>> >> >
>> >> > --
>> >> > Sanket Jain
>> >> >
>> >
>> >
>> >
>> > --
>> > Sanket Jain
>> >
>
>
>
> --
> Sanket Jain
>